<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!-- <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js"></script> -->
    <script src="lib/jquery-3.7.1.js"></script>

</head>
<body>
<!--
    JQuery公式： $(selector).action();
-->
    <a href="" id = "test_jquery">点我</a>

<script>
    document.getElementById('test_jquery');
    //选择器就是CSS的选择器
    $('#test_jquery').click(function (){
        alert('Hello JQuery!');
    });
</script>
</body>
</html>